U.S. patent number 10,011,325 [Application Number 14/965,648] was granted by the patent office on 2018-07-03 for linear derailleur mechanism.
This patent grant is currently assigned to Yeti Cycling, LLC. The grantee listed for this patent is YETI CYCLING, LLC. Invention is credited to Peter Zawistowski.
United States Patent |
10,011,325 |
Zawistowski |
July 3, 2018 |
Linear derailleur mechanism
Abstract
A derailleur system is provided that moves the derailleur cage
in a substantially rectilinear path. The derailleur is mounted to a
frame having a gear cassette mounted thereon. The gear cassette
includes an axis of rotation. The derailleur includes a drive
member engaging the gear cassette. The derailleur is positioned on
the frame adjacent the gear cassette, and including a spatial
linkage having a stationary link, a floating link, and a cage
assembly having two pulleys each defining an axis of rotation. The
drive member engages each of the pulleys. The path of the floating
link is substantially linear through substantially its entire range
of motion and variously aligns at least one of the pulleys with the
gear cassette.
Inventors: |
Zawistowski; Peter (Lakewood,
CO) |
Applicant: |
Name |
City |
State |
Country |
Type |
YETI CYCLING, LLC |
Golden |
CO |
US |
|
|
Assignee: |
Yeti Cycling, LLC (Golden,
CO)
|
Family
ID: |
55066827 |
Appl.
No.: |
14/965,648 |
Filed: |
December 10, 2015 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20160167740 A1 |
Jun 16, 2016 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62090220 |
Dec 10, 2014 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62M
9/1242 (20130101); B62M 9/122 (20130101); B62M
9/1342 (20130101); B62M 9/132 (20130101) |
Current International
Class: |
F16H
9/00 (20060101); F16H 63/00 (20060101); B62M
9/122 (20100101); B62M 9/1342 (20100101); F16H
61/00 (20060101); F16H 59/00 (20060101); B62M
9/1242 (20100101); B62M 9/132 (20100101) |
Field of
Search: |
;474/80,82 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2540609 |
|
Jan 2013 |
|
EP |
|
H0725378 |
|
Jan 1995 |
|
JP |
|
Other References
Chen, "Design of Structural Mechanisms", A dissertation submitted
for the degree of Doctor of Philosophy in the Department of
Engineering Science at the University of Oxford, St Hugh's College,
2003, 160 Pages. cited by applicant .
International Bureau, "International Search Report and Written
Opinion", PCT Patent Application No. PCT/US2015/065090, dated Feb.
23, 2016, 11 Pages. cited by applicant .
Li, "Movable Spatial 6R Linkages", XP055249075, Retrieved from the
Internet on Oct. 13, 2016:
URL:http://people.ricam.oeaw.ac.at/z.li/publications/talks/6.pdf,
Oct. 2, 2013, 48 Pages. cited by applicant .
Sarrut, "Note Sur La Transformation Des Mouvements Rectilignes
Alternatifs", Academie des Sciences, 36, 1036-1038, 1853, 5 Pages.
cited by applicant .
Zawistowski, "Quantifying Wheel Path", Think Turquoise,
http://www.yeticycles.com/blog/?p=237 [Retrieved from the Internet
on Jul. 27, 2011], Jul. 18, 2010, 4 Pages. cited by
applicant.
|
Primary Examiner: Liu; Henry Y
Attorney, Agent or Firm: Dorsey & Whitney LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application
No. 62/090,220 filed on, Dec. 10, 2014 entitled "Linear Derailleur
Mechanism," the content of which is hereby incorporated by
reference in its entirety.
Claims
I claim:
1. A bicycle comprising: a frame having a gear cassette mounted
thereon, the gear cassette having an axis of rotation; a drive
member engaging the gear cassette; a derailleur positioned on the
frame adjacent the gear cassette, with the derailleur having a cage
assembly with two pulleys each defining an axis of rotation and the
drive member engaging each of the pulleys, wherein the derailleur
also includes a spatial linkage having: a stationary link and a
floating link wherein the path of the floating link is
substantially linear through substantially its entire range of
motion.
2. The bicycle of claim 1, wherein the gear cassette is a rear gear
cassette operably associated with a rear wheel.
3. The bicycle of claim 1, wherein the gear cassette is a front
chain ring set operably associated with a crank.
4. The bicycle of claim 1, wherein the pulley axes of the cage
assembly is parallel to the axis of rotation of the gear cassette
and remains parallel to the axis of rotation of the gear cassette
throughout its entire range of motion.
5. The bicycle of claim 1, wherein the pulley axes of the cage
assembly is not parallel to the axis of rotation of the gear
cassette and remains not parallel to the axis of rotation of the
gear cassette throughout its entire range of motion.
6. The bicycle of claim 1, wherein the spatial link is an
over-constrained spatial 6R linkage.
7. The bicycle of claim 1, wherein the stationary link is attached
to the bicycle frame.
8. The bicycle of claim 1, wherein the cage assembly is pivotally
connected concentrically on the floating link.
9. The bicycle of claim 1, wherein the cage assembly is pivotally
connected eccentrically on the floating link.
10. The bicycle of claim 1, wherein an actuation force is applied
to the derailleur to cause motion from a first position to a second
position, and at least one return mechanism is utilized to urge the
derailleur from the second position towards the first position.
11. The bicycle of claim 10, wherein the actuation force may be
mechanically, electrically, or hydraulically driven.
12. The bicycle of claim 11, wherein the return mechanism may
include at least one spring selected from one of the group of a
torsion spring, and/or an extension spring.
13. The bicycle of claim 11, wherein input activation of the
linkage is via a mechanical cable.
14. A derailleur for a bicycle comprising: a stationary link and a
floating link wherein the path of the floating link is
substantially linear through substantially all of the floating
link's range of motion, wherein the floating link is operable to
move a drive member which is operable to engage a gear cassette,
wherein the stationary link is operable to be positioned on a
frame, the gear cassette having an axis of rotation, wherein the
stationary link is positioned on the frame adjacent the gear
cassette and the stationary link and a floating link form an
over-constrained spatial 6R linkage.
15. A derailleur of claim 14, wherein the gear cassette is a rear
gear cassette operably associated with a rear wheel.
16. A derailleur of claim 14, wherein the gear cassette is a front
gear cassette operably associated with a crank.
17. The derailleur of claim 14, wherein the pulley axes of the cage
assembly remain parallel to the axis of rotation of the gear
cassette throughout its entire range of motion.
18. The derailleur of claim 14, wherein the stationary link is
connected to the bicycle frame.
19. The derailleur of claim 14, wherein the cage assembly is
pivotally connected concentrically on the floating link.
20. The derailleur of claim 14, wherein the cage assembly is
pivotally connected eccentrically on the floating link.
21. The derailleur of claim 14, wherein an actuation force is
applied to the derailleur to cause motion from a first position to
a second position, and at least one return mechanism is utilized to
urge the derailleur from the second position towards the first
position.
22. The derailleur of claim 21, wherein the actuation force is
mechanically, electrically, or hydraulically driven.
23. The derailleur of claim 21, wherein the return mechanism
includes at least one spring selected from one of the group of a
torsion spring, and/or an extension spring.
24. The derailleur of claim 22, wherein input activation of the
linkage is via a mechanical cable.
25. The derailleur of claim 22, wherein input activation of the
linkage is via an electronic servo.
26. The derailleur of claim 22, wherein the input activation of the
linkage is via a piston.
27. A bicycle comprising: a frame having a gear cassette mounted
thereon, the gear cassette having an axis of rotation; a drive
member engaging the gear cassette; a derailleur positioned on the
frame adjacent the gear cassette, with the derailleur having a
stationary link and a floating link, wherein the stationary link is
connected to the floating link via a first linkset and a second
linkset, each linkset having a plurality of axis of rotation,
wherein the axes of rotation in the first linkset are not parallel
to the axes of rotation in the second linkset.
28. The bicycle of claim 27, wherein the derailleur includes a cage
assembly in direct association with the floating link, the cage
assembly includes two pulleys each defining an axis of rotation and
the drive member engaging each of the pulleys.
29. The bicycle of claim 28, wherein the first linkset includes a
first end and a second end, wherein the first end includes a
pivoting connection with the stationary link and the second end
includes a pivoting connection with the floating link.
30. The bicycle of claim 29, wherein the first linkset includes a
first link and a second link and the second linkset includes a
first link and a second link.
Description
TECHNICAL FIELD
Discussed herein is a bicycle derailleur and, with more
particularity, a derailleur at operates in a linear motion shifting
the bicycle drive between cassette cogs.
BACKGROUND
Bicycles are commonly provided with a series of parallel
cogs/sprockets of varying diameter/tooth-counts fixed to the rear
wheel of the bicycle concentric to the wheel axis, also considered
a rear gear cassette. The cogs are typically arranged in a
cone-like shape from small gear to large gear. A bicycle rider
transfers power via the cranks (having a crank axis) in which a
front chain ring is fixed. The front chain ring may include more
than one cog/sprocket having differing sizes (e.g. also forming a
cone) and be considered a front gear cassette. A drive chain/belt
travels over the chain/belt ring to one of the rear cogs in a
closed loop, driving the rear wheel.
The gear ratio between the front chain ring (power input) and rear
wheel (power output) is determined by which rear cog the drive
chain/belt has engaged. An example of a prior art rear derailleur
used to shift the chain/belt is disclosed in FIG. 1. The rear
derailleur 10 is a linkage mechanism that controls the position of
the drive chain/belt 5 relative to individual cogs/sprockets 6 of
the rear wheel. Currently, a linkage used in a rear derailleur 10
such as those commonly used today is a 2-dimensional planar 4-bar
linkage 11 having a parallelogram structure. The resultant path of
the floating link 20 of this mechanism is non-linear, forming a
curved or arcuate path. As a result, the angle of the derailleur
pulley axes 17, 19 are not constant relative to the wheel axis 7 in
at least one reference plane throughout the entire travel range,
which can create undesirable forces and negatively affect
performance and wear and tear on the components. The wheel axis 7
is the axis defined by the rotation of the wheel hub 2.
Typical rear derailleurs 10 have of a parallelogram linkage 11 as
shown in FIG. 1. One link, the stationary link 14, is fixed or
pivotally mounted at connection 12 to the rear derailleur hanger 3
of the bicycle rear triangle 1 or swingarm, or to the rear
triangle/swingarm itself. Two parallel links 16, 18 connect the
floating link 20 to the stationary link 14. An actuation force is
applied to change the position of the mechanism, typically via a
cable. A return spring is connected to the parallelogram providing
a force opposite to that of the actuation force. A derailleur cage
assembly 30 is pivotably connected to the floating link 20. The
derailleur cage assembly includes an upper pulley or jockey pulley
31, and a lower pulley or idler pulley 32.
Currently the most common linkage design used in rear derailleurs
today is a planar 4-bar linkage parallelogram. There are several
disadvantages to this mechanism. For example, the resultant path
this linkage defines is non-linear curved. As a result, the angular
relationship of the derailleur pulley axes 17, 19 varies with
respect to the wheel axis 7 throughout the range of motion. The
inherent geometry of the parallelogram leaves little freedom of the
linkage mounting location relative to the rear wheel to achieve the
desired linkage path. This limited freedom correspondingly limits
frame designers options, whereas more freedom of this mounting
location would give frame designer more options.
As noted previously, derailleur linkages 11 are activated via an
actuation force to move the mechanism through its travel. Moving
the mechanism through its travel causes the chain 5 to shift from
one wheel cog in the cassette 6 to another wheel cog. One end of
the actuation cable is connected to one of the non-stationary links
20 and the other to the stationary link 14 or bike frame itself.
With a parallelogram design, the mechanism's linkage path is
dependent upon the link lengths and axes geometry. In order to
achieve an optimum linkage path and actuation ratio in a
parallelogram mechanism, it is common to add additional complex
features such as pulley wheels and extended links. These items add
weight and complexity.
The inherent geometry of the parallelogram leaves little freedom to
minimize the mechanism's volume envelope and envelope position
relative to the drive side frame dropout. It is desirable to have a
compact mechanism located as inboard as possible to the frame to
minimize the chance of hitting the derailleur on an obstacle while
riding, which can prove difficult to achieve with this design.
A mechanism that offers various solutions to the inherent
mechanical limitations of a parallelogram design discussed above is
desired.
SUMMARY
In accordance with various embodiments, a bicycle may include a
frame having a gear cassette mounted thereon, the gear cassette
having an axis of rotation, and a drive member engaging the gear
cassette. The bicycle may also include a derailleur positioned on
the frame adjacent the gear cassette, and including a linear
linkage. The linear linkage may include a stationary link and a
floating link. The derailleur may include a cage assembly having
two pulleys each defining an axis of rotation. The drive member may
engage each of the pulleys. The path of the floating link may be
substantially linear through substantially all of its range of
motion.
In accordance with various embodiments, the gear cassette may be a
rear gear cassette operably associated with a rear wheel. The gear
cassette is a front chain ring set operably associated with a
crank. The pulley axes of the cage assembly may be parallel to the
axis of rotation of the gear cassette and remains parallel to the
axis of rotation of the gear cassette throughout its entire range
of motion. The pulley axes of the cage assembly is not parallel to
the axis of rotation of the gear cassette and remains not parallel
to the axis of rotation of the gear cassette throughout its entire
range of motion. The spatial link may be an over-constrained
spatial 6R linkage. The fixed link may be attached to the bicycle
frame. The cage assembly may be pivotally connected concentrically
on the floating link. The cage assembly may be pivotally connected
eccentrically on the floating link.
In accordance with various embodiments, an actuation force may be
applied to the derailleur to cause motion from a first position to
a second position. At least one return mechanism may be utilized to
urge the derailleur from the second position towards the first
position. The actuation force may be a mechanically, electrically,
or hydraulically driven. The return mechanism may include at least
one spring selected from one of the group of a torsion spring,
and/or an extension spring. The input activation of the linkage may
be via a mechanical cable. The input activation of the linkage may
be via an electronic servo. The input activation of the linkage may
be via a hydraulic plunger.
In accordance with various embodiments, a derailleur for a bicycle
may include a frame having a gear cassette mounted thereon. The
derailleur may also include a stationary link and a floating link.
The path of the floating link may be substantially linear through
substantially all of the floating link's range of motion. The
floating link may be operable to move a drive member. The drive
member may be operable to engage a gear cassette. The stationary
link may be operable to be biased to be substantially stationary
relative to a frame having the gear cassette mounted thereon. The
gear cassette may have an axis of rotation. The stationary link may
be positioned on the frame adjacent the gear cassette.
In accordance with various embodiments, the gear cassette is a rear
gear cassette operably associated with a rear wheel. Alternatively,
the gear cassette may be a front gear cassette operably associated
with a crank. The pulley axes of the cage assembly may remain
parallel to the axis of rotation of the gear cassette throughout
its entire range of motion. The linear derailleur may include a
spatial link that is an over-constrained spatial 6R linkage. The
Stationary link may be positioned relative to and attached directly
or indirectly to the bicycle frame. The cage assembly may be
pivotally connected concentrically on the floating link. The cage
assembly may be pivotally connected eccentrically on the floating
link. An actuation force may be applied to the derailleur to cause
motion from a first position to a second position, and at least one
return mechanism may be utilized to urge the derailleur from the
second position towards the first position. The actuation force may
be a mechanically, electrically, or hydraulically driven. The
return mechanism may include at least one spring selected from one
of the group of a torsion spring, and/or an extension spring. The
input activation of the linkage may be via a mechanical cable. The
input activation of the linkage may be via an electronic servo. The
input activation of the linkage may be via a hydraulic plunger.
In accordance with various embodiments, a bicycle may include a
frame having a gear cassette mounted thereon, the gear cassette
having an axis of rotation, and a drive member engaging the gear
cassette. The bicycle may also include a derailleur positioned on
the frame adjacent the gear cassette. The derailleur may have a
stationary link and a floating link. The path of the floating link
may be substantially linear through substantially its entire range
of motion. The stationary link may be connected to the floating
link via a first linkset and a second linkset. Each linkset may
have a plurality of axes of rotation. The axes of rotation in the
first link set are not parallel to the axes of ration in the second
linkset.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a typical embodiment of a prior art rear
derailleur for a bicycle;
FIG. 2 illustrates an isometric view of a rear wheel of a bicycle
having a derailleur;
FIG. 3A illustrates an isometric rear view of a linear derailleur
in accordance with an exemplary embodiment;
FIG. 3B illustrates an isometric side view of a retracted
configuration of the linear derailleur of FIG. 3A in accordance
with an exemplary embodiment;
FIG. 3C illustrates an isometric side view of an extended
configuration of the linear derailleur of FIG. 3A in accordance
with an exemplary embodiment;
FIG. 3D illustrates a isometric rear view of the derailleur of FIG.
3A in accordance with an exemplary embodiment;
FIG. 4A illustrates an exploded view of an exemplary linkage of a
linear derailleur;
FIG. 4B illustrates an isometric view of a plurality of different
positions along a linear path;
FIG. 4C illustrates an isometric view of an example linkage with
linksets having different axes of rotation;
FIG. 4D illustrates an isometric view of a counter example linkage
with linksets having parallel axes of rotation;
FIG. 4E illustrates an isometric view of an example linkage with a
cross configuration;
FIG. 4F illustrates an alternate isometric view of an example
linkage with a cross configuration;
FIG. 4G illustrates an isometric view of an example linkage with an
open configuration;
FIG. 4H illustrates an alternate isometric view of an example
linkage with an open configuration;
FIG. 5A illustrates a side view of a linear derailleur in
accordance with an exemplary embodiment;
FIG. 5B illustrates a rear view of the linear derailleur of FIG. 5A
in accordance with an exemplary embodiment;
FIG. 5C illustrates a top view of the linear derailleur of FIG. 5A
in accordance with an exemplary embodiment;
FIG. 5D illustrates a side isometric view of the linear derailleur
of FIG. 5A in accordance with an exemplary embodiment;
FIG. 5E-F illustrate a rear view of extended and contracted linear
derailleurs in accordance with an exemplary embodiment;
FIG. 6A-B illustrate a side view of a concentric linear derailleur
in accordance with an exemplary embodiment;
FIG. 7A-B illustrate a side view of an eccentric linear derailleur
in accordance with an exemplary embodiment;
FIG. 8 illustrates an isometric rear view of a linear derailleur in
accordance with an exemplary embodiment;
FIG. 9A-B illustrate rear and top isometric views of a linear
derailleur in accordance with an exemplary embodiment;
FIG. 10 is a graph comparing the horizontal derailleur movement of
various derailleurs with the resultant angles of the pulley axes as
the yaw and roll;
FIG. 11 is a graph comparing the horizontal derailleur movement of
various derailleurs with the resultant angles of the pitch of the
pulley axes;
FIG. 12 is a graph comparing the horizontal derailleur movement of
various derailleurs with the resultant angles of the pulley axes as
the yaw and roll;
FIG. 13 is a graph comparing the horizontal derailleur movement of
various derailleurs with the resultant angles of the pitch of the
pulley axes; and
FIG. 14 is a graph comparing the derailleur movement with the
actuation movement.
DETAILED DESCRIPTION
The present disclosure is related to a derailleur mechanism for a
bicycle used to change the position of the drive chain relative to
individual cogs/sprockets on the bicycle drive train. In one
example, the cogs/sprockets are a part of the rear dive mechanism
on the rear wheel. The drive chain is moved via a remote control
known as a shifter. A change in the active rear wheel drive cog
changes the gear ratio between the front chain-ring (power input)
and rear wheel (power output).
The present disclosure differs from traditional derailleurs in that
the derailleur pulley axes remain substantially constant relative
to the wheel axis throughout the entire travel range. This
particular relative movement is achieved by providing a derailleur
with a linear linkage mechanism. As an example, the linear
derailleur includes an over-constrained 6R spatial linkage (e.g. a
Sarrus linkage) which is capable of substantially linear motion of
the floating link. As a result, the angles of the pulley axes and
the wheel or crank axis remain constant relative to one another.
This linear motion allows for either of a concentric or eccentric
mounting of the derailleur cage on the linkage system.
Despite being discussed in the embodiment of a rear derailleur
herein, a person of ordinary skill in the art will appreciate that
the concepts and elements of the linear derailleur 100 can also be
adapted to be utilized as a front derailleur on a bicycle in
addition to or in the alternative of a rear derailleur. However, as
an example to be discussed in more detail herein and as shown in
FIG. 2, the linear derailleur 100 may hang from the rear triangle 1
of a bicycle in order to shift the drive mechanism 5 (e.g. chain
belt or the like) between the rear cogs on a cassette 6. As a
matter of orientation and as shown in FIG. 2, the forward direction
may be in the X direction, the upward direction may be in the Y
direction, and the front side direction may be in the Z direction,
which is shown at the rear wheel rotation axis.
In accordance with various embodiments, a bicycle includes a linear
derailleur 100. For example, the linear derailleur is a rear
derailleur 100. As illustrated by way of example in FIG. 3A, the
linear derailleur 100 includes a hanger 3 which hangs from the rear
triangle 1 (not shown) to suspend the derailleur 100 from the
bicycle.
In the various embodiments, the linear derailleur 100 includes a
movable connection 110. The movable connection 110 is formed of a
mechanism operable to drive at least a portion of the cage assembly
30 in a linear path. In one example, the movable connection 110
includes a stationary link 140 that is connected relative to a bike
frame, e.g. via the hanger 3 or in some embodiments directly
connected to the bike frame 1. In one example, the stationary link
140 is substantially fixed relative to the bike frame. While the
term fixed is used herein, it should be appreciated that, the
stationary link 140 may have one or more degrees of freedom such as
being rotatable relative to the bike frame. This freedom may be
substantially limited via use of biasing springs. The degrees of
freedom may also or alternatively be restrained via a fastener or
similar means such that the stationary link 140 maintains a
substantially consistent position relative to the bike frame after
assembly. The stationary link 140 may be adjustable via a torsion
screw that is operable to make minor adjustments to better
calibrate the stationary link and the derailleur in general
relative to the cassette. A person of ordinary skill in the art
will appreciate typical methods from mountain a stationary link 140
based on understanding of the art and disclosure provided
herein.
In various examples, the movable connection 110 includes a floating
link 150 that is movably connected to the stationary link 140. The
floating link 150 moves in a substantially rectilinear relationship
to the stationary link 140. As such, the floating link 150 is
substantially constrained to a single rectilinear degree of
freedom. While particular mechanisms that connect the floating link
150 to the stationary link 140 are discussed herein in greater
detail, it should be appreciated by a person of ordinary skill in
the art that other rectilinear connections may be incorporated as
well. For example, the floating link 150 to the stationary link 140
can be connected via a linear rail mechanism or other linear
mechanisms suitable to maintain the rectilinear degree of movement
between the floating link 150 and the stationary link 140.
The stationary link 140 includes a frame connection operable to
keep the stationary link 140 positioned relative to the frame as
discussed above. In one example, the stationary link 140 is
contiguously formed with the frame. In another example, the
stationary link 140 is removably connected directly to the frame.
In another example, the stationary link 140 is connected to a frame
bracket (e.g. a derailleur hanger 3).
In accordance with various embodiments, the derailleur 100 includes
an actuator 170 that is operable to move the stationary link 140
and the floating link 150 relative to one another. The stationary
link 140 may have a bracket 162 operable to retain, contact, or
mount an actuator to form an actuator mounting feature. In one
example, as shown in FIGS. 3A-C, the stationary link may have a
bracket 162 suitable for retaining cable 170 forming a cable
bracket. In the example, the cable bracket 162 is operable to house
the cable and/or mount a cable adjustment barrel to the stationary
link 140. However, other actuator setups are also envisioned herein
as discussed herein with regards to FIGS. 8-9, which variously show
setups including a piston/linear servo set up and a rotary servo
set up variously mounted to the stationary link 140.
In accordance with various embodiments, the derailleur 100 includes
a biasing mechanism 132 that is operable to return the stationary
link 140 and the floating link 150 to an unactuated position in the
absence of an opposing force from actuator 170. The stationary link
140 may also have a mount 130 for a biasing mechanism 132. A
biasing mechanism may be operable to return the derailleur system
to a compressed, extended, or intermediate state absent force from
the actuator. As an example, mount 130 may retain an extension
spring on the stationary link 140. A second mount 134 may be
positioned on the movable connection 110 and operable to retain the
opposite end of the biasing mechanism 132. Other mechanisms may be
used in addition to or as alternatives to the extension spring. For
example, as shown in FIG. 3D one or more torsion springs 155 may be
attached between the various links (e.g. a first link 152 and the
stationary link 140 discussed in more detail herein) to bias the
floating link 150 toward an unactuated position such as the
collapsed configuration shown. As such, a derailleur cage assembly
30 that includes of an upper pulley or jockey pulley 31, and a
lower pulley or idler pulley 32 is pivotably attached to the
floating link 150. One or more return springs 132 or 155 can be
used to provide a force opposite to that of the actuation force. By
way of example, these biasing mechanisms 132 can be torsion springs
155 located at one or more of the linkage pivots, or one or more
extension springs 132 connected to two points in the mechanism.
However, it is appreciated that other biasing mechanism may be used
as well.
In accordance with various embodiments, the derailleur 100 includes
a cage assembly 30 comprising jockey and idler pulleys. In various
examples, the floating link 150 includes a cage hanger portion 151
operable to keep the floating link 150 positioned relative to the
derailleur cage 130. The floating link 150 may be contiguously
formed with the derailleur cage 30, connected directly to the
derailleur cage 30, or connected to a bracket extending from the
derailleur cage 30. In this way, at least a portion of the
derailleur cage 30 moves in the same rectilinear motion as the
floating link 150. This movement may allow the derailleur cage 30
to align with the cassette 6 such that the chain/belt 5 can move
between separate gear rings. The mount between the floating link
150 and the derailleur cage 30 may be concentric with the jockey
pulley or it may be eccentric with the jockey pulley.
In accordance with various embodiments, the movable connection 110
may be formed via one or more link sets. For example, the
connection 110 includes a first link set 145a and a second link set
145b. The first link set 145a includes a first link 152 and a
second link 154 that are rotatably connected to each other at a
hinge 156. The second link set includes a third link 142 and a
fourth link 144 that are rotatably connected to each other at a
hinge 148. One or more of the links such as link 152, as shown in
the FIGS. 3A-C, may include a link extension 153 that is connected
to an actuator 170 (e.g. actuation cable or piston). From this
position, the actuator 170 can contract the link extension 153
toward the actuator mount 162. This action causes the floating link
150 to extend away from the stationary link 140 in a rectilinear
path. In other embodiments, a servo may rotate link 152 with
respect to the stationary link 140 similarly causing the floating
link to extend away from the stationary link.
Each of the first link set 145a and the second link set 145b are
rotatably connected to each of the stationary link 140 and the
floating link 150 via hinges 146, 149, 158, and 159. For example,
the stationary link 140 may include the first hinge joint 146 and
the second hinge joint 149 operable to connect to links 152 and
142, respectively. The floating link 150 may include the third
hinge joint 158 and a fourth hinge joint 159 as shown in FIG. 3B.
The joints 158, 159 are operable to connect the floating links to
links 154 and 144, respectively.
In accordance with various embodiments and as discussed above, the
movable connection 110 is a linkage that provides a single degree
of freedom in a rectilinear motion. For example, the movable
connection 110 is an over-constrained 6R spatial linkage (such as
e.g. a Sarrus linkage) which is capable of providing substantially
rectilinear motion between the stationary link 140 and the floating
link 150. Such a structure allows the derailleur 100 to have a
substantially rectilinear motion created by the over-constrained 6R
spatial linkage (such as a Sarrus linkage). This structure
overcomes the non-linearity issues associated with a typical
derailleur structure. Furthermore, this derailleur structure also
may allow a smaller package to reduce interference with other
components or ground effects during riding. The Sarrus linkage is
an example of a 6R spatial mechanism. A 6R spatial mechanism is one
that includes 6 links with revolute joints and at least one link
axis is not parallel to another within the system. Accordingly, the
Sarrus linkage is significantly different than the traditional
parallelogram linkage typically used in derailleurs today.
In accordance with various embodiments, each of the hinges of the
movable connection 110 has an axis. At least one of the axes
through the hinge joints of the movable connection 110 forms an
angle other than 0 degrees or 180 degrees with respect to at least
one other axis. The two axes may, however, be planar or skew with
respect to each other. In various embodiments, each of the hinge
axes associated with the first link set 145a are parallel and each
of the hinge axes associated with the second link set 145b are
parallel. However, in this embodiment, the hinge axes of the first
link set 145a and the hinge axes of the second link set 145b are
not parallel.
The following information related to an over-constrained mechanical
system is provided below to provide a broader understanding of the
applicability, structure and theory of the system without any
intention on being bound by the theory provided herein. As
indicated above, a 6R spatial linkage, such as a Sarrus linkage,
may be incorporated into a derailleur system, which may be used in
the various structure provided herein. Such a linkage may include
two special properties: 1) It is an over-constrained mechanism; and
2) The linkage is capable of rectilinear motion.
To touch on the theory underlying various linkages, the following
analysis known as the Mobility Analysis of Mechanisms (Kutzbach (or
Grubler) mobility criterion) can be used to describe the mobility
of a linkage. The mobility m of a linkage composed of n links that
are connected with p joints: mobility=m=6(n-p-1)+.SIGMA.f
n=number of links
p=number of joints
.SIGMA.f=sum of the kinetic variables in the mechanism
Revolute joints or rotary hinges allow one degree of freedom
movement between the two links they connect. For an n-link closed
loop linkage with revolute joints: .SIGMA.f=n p=n m=6n-6p-6+n
m=6n-6n-6+n m=n-6 So in general, to obtain a mobility of one a
linkage with revolute joints needs at least seven links. However,
it was found that this criterion is not always a necessary
condition to achieve mobility. It is possible for there to be a
specific geometric condition of a linkage allowing mobility even
though it does not obey the mobility criterion. This type of
mechanism is called an over-constrained mechanism. In the case of a
Sarrus linkage: m=6-6=0 However, the Sarrus Linkage has m=1 which
makes it over-constrained.
As illustrated in the schematic diagram of the linkage system
provided in FIGS. 4A-D, an over-constrained 6R spatial linkage and
its links include a stationary link 140 corresponding to the fixed
side of the linkage and a set of non-stationary links. The
non-stationary links include floating link 150, linkset 145a, and
linkset 145b. The linkset 145a may include links 142 and 144. The
linkset 145b may include links 152 and 154. As illustrated in this
example, all three axes N, P, and R of linkset 145a are parallel.
Additionally, as illustrated in this example, all three axes M, Q,
and S of linkset 145b are parallel.
In accordance with various embodiments, each of a pair of end links
(e.g. the stationary link 140 and the floating link 150) can
include two rotatable connection portions such as connectors 141a,
141b or 151a, 151b. Each mid link such as linkset 154a and 145b
includes rotatable connection portions (e.g. 155a, 157b, 143a, or
147b) that are operable to engage with the connectors of the end
links. The connections may be made via the matching of the
rotatable axes of each component piece as shown for example in FIG.
4A. For example, M of link 140 with M of link 152, S of link 154
with S of link 150, R of link 150 with R of link 147b, and N of
link 142 with N of link 140. This assembly allows for the linear
actuation of an example of the motion mechanism 110 in a linear
derailleur 100. As shown in FIG. 4B, the rectilinear path of
floating link 140 relative to stationary link 150 basses through
the adjacent linear positioned denoted by A, B, and C in the
figure. A is a collapsed position. B is an intermediate linear
position. C is an expanded linear position.
Again not to be bound by theory but to provide a broader
disclosure, it is understood theoretically that in order for the
spatial linkage to constrain the floating link 150 to a rectilinear
path, certain conditions should be met. In one embodiment, with a
6R linkage, R denoting revolute joints or rotary hinges that allow
one degree of freedom movement between links (see e.g. FIG. 4A),
all three pivot axes of the first linkset 145a are be parallel to
each other, all three pivot axes of the second linkset 145b are
parallel to each other, and the first linkset's pivot axes N, P,
and R are not parallel to the second linkset's 145b pivot axes M,
Q, and S. Such a system is illustrated in FIG. 4C. The floating
link is constrained to a rectilinear path and may be suitable for
use in one or more of the various linear derailleur embodiments as
described in this disclosure.
The structure provided herein allows for great flexibility to tune
the mechanism to have the desired design goals since many variables
can be modified. For example, the linksets can be configured in a
crossed configuration as illustrated in FIGS. 4E and 4F. Or in
another example, the linksets can be configured in an open
configuration as illustrated in FIGS. 4G and 4H.
The mounting positions on the stationary and floating links can
vary as well. For example, the floating link 150 can have longer or
shorter connection portions 151a, 151b. In another example, the
stationary link 140 can have longer or shorter connection portions
141a, 141b. Additionally or alternatively, the pivot axes can be
rotated. Additionally, the mechanism can be rotated and still
achieve the same linear motion. In the various embodiments, the
lengths of links 142, 144, 152 and 154 can vary independently of
the mechanism's 110 linear motion. With rectilinear actuation, the
mechanism 110 can be rotated in any direction and the travel of the
floating link 150 is the same linear path. In a structure that
holds the bottom link portion stationary (e.g. stationary relative
to the bike frame), the upper floating link moves linearly along
the path A, B, and C shown in FIG. 4B. With the mechanism rotated
90 degrees and the lower link stationary, the upper link still
moves in the same linear fashion in the exact same path. This is in
contrast to the traditional parallelogram linkage, which would have
an output motion that is curvilinear. That curvilinear path would
also rotate 90 degrees, creating a new orientation in contrast to
the mechanism illustrated in FIGS. 4A-H. By maintaining the same
path independent of the lower/upper link rotation orientation,
there is a lot of flexibility in setting the linkage orientation
while achieving the same or substantially similar resultant path of
travel.
Modifying the adjustable variables affects many attributes of the
linkage but do not necessarily affect the linear path. A few
examples of the attributes that may be affected by the adjustable
variables include stiffness, travel range, packaging, mechanism
envelope, actuation ratio relative to motion, and actuation
point.
With regards to stiffness, the lateral stiffness of the mechanism
110 changes depending on the linkset angles and individual link
lengths. This stiffness change is in addition to the link depth and
width, the material, and the pivot construction, e.g.
bearing/bushing and axle type/size. For instance, the closer 145a
and 145b are to perpendicular, the stiffer the linkage generally
is. So although theoretically the linksets' 145a and 145b axes are
operable to achieve linear motion of the floating link with the
axes slightly out of parallel, in practicality this would be
difficult to achieve due to flex in individual links and revolute
joint tolerances. As such, as angles between the linksets'
respective axes angles approach perpendicular, the stiffness is
increased. With regards to travel range, the longer the links 142,
144, 152 and 154, typically the longer the travel range. As such,
by maximizing the length of the links 142, 144, 152 and 154
relative to the desired package size, the travel of the derailleur
is maximized.
With regards to packaging, meaning the location of the derailleur's
fixed side mounting, the fixed link can be located in many
locations in 3d space to achieve the same linear path. The linear
derailleur is not sensitive to the orientation of the stationary
link 140's position because the movement is rectilinear from that
location, whereas systems with a curvilinear path are sensitive to
the orientation of the stationary link. With regards to the
mechanism envelope, the linkset's location and orientation can be
configured to minimize the mechanism envelope. For example and as
illustrated in FIG. 4E-4F, the linkset 145a and the linkset 145b
can be placed into a crossed pattern so that the linksets 145a and
145b fold in on themselves to save space. The cross pattern is also
helpful to prevent interference between the links during the travel
range. Alternatively as illustrated in FIG. 4G-4H, the linkset 145a
and the linkset 145b can be placed into an open configuration. An
open configuration provides additional packaging room between the
station link 140 and the floating link 150 that could be occupied
by additional derailleur features.
With regards to actuation ratio relative to motion, the actuation
ratio can be changed simply by modifying individual link 142, 144,
152 and 154 lengths. This can be done with little to no effect on
the constrained linear motion of the mechanism. With regards to
actuation point, any non-stationary link can be used to activate
the motion of mechanism 110 motion. Utilizing any non-stationary
link provides options in design since the envelope and packaging of
various alternative portions of the derailleur can be utilized with
the linear derailleur. Thus, more design freedom is allowed.
Referring back to FIG. 2, a global coordinate system relative to a
bicycle is provided. The origin is coincident to the rear axle axis
and the centerline of the bike. X-positive is the direction the
bicycle travels straight forward. Y-positive is upwards direction
perpendicular to the ground. Z-positive is collinear to the wheel
axis pointing towards the drive-side of the bicycle. Therefore, the
cassette sprockets and front chain-ring(s) are parallel to the XY
plane. Furthermore, the global axes of rotation of this coordinate
system are also defined. X is the roll axis, Y is the yaw axis, and
Z is the pitch axis. The standard right-hand rule denotes
polarity.
In the traditional linkage design used in rear derailleurs, e.g. a
planar 4-bar linkage forming a parallelogram, the resultant path
defined is non-linear or curvilinear. The axes of the parallelogram
are not parallel to the wheel axis. As a result, the upper and
lower pulley axes do not remain parallel to the wheel axis
throughout the entire range of motion. In contrast, the linear
derailleur, such as one with a spatial linkage, constrains the path
of the rear derailleur floating link 150 to a substantially
rectilinear motion. This is unique in that the spatial linkage
constrains the floating link 150 to a substantially rectilinear
path as opposed to a non-linear or curvilinear path. The
rectilinear path that the floating link 150 and, therefore, the
derailleur cage 30 takes can be, but does not have to be, parallel
to the XY, YZ, or XZ planes. Depending on the design intent, the
linear path can be located anywhere in 3d space near the rear wheel
cogs.
As illustrated in FIGS. 5A-D, an example linear Path is shown in
the XY plane (FIG. 5A), YZ plane (FIG. 5B), XZ plane (FIG. 5C), and
isometric view FIG. 5D. The path in each of these views forms a
rectilinear path extending from the top right of each figure to the
bottom left. The floating link 150 and some portion of cage 30
follows these paths in their respective rectilinear motion. By
moving the cage 30 in such a consistent manner, overall shifting
and functionality of the derailleur is improved over traditional
types.
The system discussed herein may be influenced by the angular
relationship between the derailleur pulley axes and the wheel axis
throughout the travel range of the mechanism. With the global
coordinate system defined the yaw angle, the roll angle, and the
pitch angle can be discussed to define the rotation of the pulley
axes in three dimensional space. With regards to the yaw angle, the
yaw angle is the rotation of the pulley wheel axes about the global
yaw axis Y. It is the angular value of one of the pulley axes
projected onto the XZ plane measured relative to the Z axis. With
regards to the roll angle, the roll angle is the rotation of the
pulley wheel axes about the global roll axis X. It is the angular
value of one of the pulley axes projected onto the YZ plane
measured relative to the Z axis. With regard to the pitch angle,
the pitch angle is the rotation of the pulley wheel axes about the
global pitch axis Z. It is the angular value of one of the pulley
axes projected onto the XY plane measured relative to the Y
axis.
As discussed herein and illustrated in FIGS. 6A and 6B, the
derailleur cage assembly 30 includes an upper pulley or jockey
pulley 31, and a lower pulley or idler pulley 32. The derailleur
cage assembly 30 is pivotally mounted to the floating link 150.
There are many possible configurations of pivotally attaching the
derailleur cage assembly 30 to the floating link 150. The different
configurations affect the motion of the jockey 31 and idler pulley
32 throughout the travel of the derailleur 100. In one example and
as illustrated in FIGS. 6A-B, the cage assembly 30 can be mounted
on the floating link 150 with the jockey pulley 31 positioned
concentrically relative to the pivotal attachment 182. In a second
example and as illustrated in FIGS. 7A-B, the cage assembly 30 can
be mounted on the floating link 150 with the jockey pulley 31
positioned at an eccentric pivot 184, which is eccentric to the
jockey pulley 31 pivot. This eccentricity affects the motion of the
jockey pulley throughout the travel of the derailleur. With the
linear motion mechanism 110, an eccentrically mounted cage assembly
30 moves in a rectilinear path at the eccentric mount 184. Pivoting
about the eccentric mount 184 allows an alternate relative movement
between the jockey pulley 31 and the idler pulley 32, allowing for
greater flexibility in tuning the derailleur to the application.
Adjusting the linear distance L between the jockey pulley pivot 182
and the eccentric pivot 184 adjusts the relative rotation of the
jockey pulley 31 relative to the eccentric pivot 184 and the
relative rotation of the idler pulley 32 relative to the eccentric
pivot 184.
In accordance with one embodiment, the pivotal attachment between
the cage 30 and the floating link 150 (e.g. either concentrically
or eccentrically) can be oriented so that the jockey 31 and idler
pulley 32 axes are not parallel to the wheel axis indicated by Z.
This orientation can be relative to yaw, roll or pitch. As a
result, the angles A1 of the derailleur pulley 31, 32 axes relative
to the wheel axis Z remain constant throughout the entire travel
range of the mechanism. Depending on the cassette 6 and chain ring
configuration, adjustment of the angles of the derailleur pulleys
31, 32 relative to the wheel axis may optimize shifting performance
by maximizing efficiency of the chain/belt 5 and cassette 6
engagement and may minimize wear from dropped chains/belts 5.
Accordingly, in various embodiments and referring to FIGS. 5E-F,
the jockey and idler pulley axes 182, 184 are not parallel to the
wheel axis in roll. For example, the angle between the jockey and
idler pulley axes 182, 184 and the wheel axes Z is greater than 1
degree. In a more particular example, the angle between the jockey
and idler pulley axes 182, 184 and the wheel axes Z is from 1 to 5
degrees. In a still more particular example, the angle is about 2
degrees.
In accordance with one embodiment, the pivotal attachment between
the cage 30 and the floating link 150 (e.g. either concentrically
or eccentrically) can be oriented so that the jockey 31 and idler
pulley 32 axes are substantially parallel to the wheel axis
indicated by Z. Depending on the cassette and chain ring
configuration, this may optimize shifting performance by maximizing
efficiency of the chainThelt sprocket system and may minimize chain
wear from dropped chains/belts. As an example and again referring
to FIGS. 5E and 5F, the jockey and idler pulley axes 182, 184 are
substantially parallel to the wheel axis. Stated another way, the
angle between the pulley axes 182, 184 and the wheel axis Z is
approximately zero.
As noted previously, an actuation force may cause movement in the
derailleur linkage in either an electro-mechanical or mechanical
control system; there is an actuation ratio between the actuation
force input and derailleur output that dictates the amount of
relative motion the derailleur moves as the shifter is actuated.
There is a ratio between the amount of actuator movement (e.g.
cable pull, piston/linear servo throw, or radial servo rotation) to
the amount of lateral movement (movement in the direction of the
wheel axis to force the chain to shift cogs) of the derailleur.
With a typical parallelogram design, the mechanism's linkage path
is dependent upon the link lengths and axes geometry. In order to
achieve an optimum linkage path and actuation ratio in a
parallelogram mechanism, it is common to add additional complex
features such as pulley wheels and extended links. These items add
weight and complexity.
With the disclosed structure and mechanism, the lengths of the
individual links of linkset 145a and linkset 145b can vary
independently of the linear path of the mechanism. Therefore, the
actuation ratio of the mechanism can be tuned independent of the
mechanism's linear path. For example, FIG. 14 illustrates one
particular example of an actuation ratio using a mechanical cable
on a linear derailleur. As shown, the y axis of the table indicates
the distance in mm that the linear derailleur moves and the x axis
indicates the corresponding distance of cable pull to achieve the
derailleur movement.
FIGS. 10-14 are graphical representations of tests or models based
on the linear derailleurs discussed herein compared to two
different parallelogram designs provided by separate companies. In
each comparison the derailleur SRAM XX1 is provided by Company 1
and the derailleur Shimano Rdm9000 is provided by Company 2. FIGS.
10 and 12 are a graphs that shows an example model of the yaw and
roll and angle deviation of the derailleur pulley axes for two
example parallelogram linkage derailleurs compared to that of the
disclosed structure using a rectilinear linkage. Note that in FIG.
10, the pulley axes of the rectilinear linkage derailleur are
parallel to the wheel axis throughout the entire travel range in
this particular case in both roll and yaw. Both of the
parallelogram designs deviate from zero in both roll and yaw. In
FIG. 12 the pulley axes of the rectilinear linkage derailleur are
set at an angle with the yaw at about -1.5 degrees and the roll at
about -0.9 degrees. Still, the linear derailleur remains constant
through the range of travel.
FIGS. 11 and 13 are graphs that shows the pitch angle deviation of
the derailleur pulley axes for parallelogram linkage of Company 2
and Company 1 compared to that of the disclosed structure which
uses a linear derailleur linkage as discussed herein. Note that in
FIG. 11, the pulley axes of linear derailleur are parallel to the
wheel axis throughout the entire travel range throughout the entire
travel range in pitch. However both of the parallelogram designs
deviate from zero in pitch but Company 1 does remain constant in
pitch unlike Company 2. Also in FIG. 13 with the pitch set at about
90 degrees, the pulley axes of linear derailleur remain constant
relative to their initial pitch.
In accordance with various embodiments, as illustrated in FIGS. 8,
9A and 9B, the derailleur receives an actuation force that can be
controlled mechanically or electro-mechanically via a known shifter
mechanism or electro-mechanical mechanism typically located on or
near the handlebars. The actuation force applied can be applied
through but is not limited to a mechanical cable (see e.g. FIG. 3A
actuator 170), linear/radial electro-mechanical servo (see e.g.
FIGS. 9A and 9B actuator 370) or a hydraulic/pneumatic cylinder
(see e.g. FIG. 8 actuator 270). In the electro-mechanical control
case, the applied actuation force is controlled by an
electro-mechanical shifter which is connected to a micro-processor
and battery to logically control the desired actuation force and
therefore derailleur output motion. In the mechanical control case,
the applied actuation force is controlled by a mechanical shifter
to mechanically control the desired actuation force and therefore
derailleur output motion. Derailleurs are positioned on the bike
frame near the front, rear, or both gear cassettes. In embodiments
having a rotary servo 370, the servo 370 drives one of the
non-stationary links 150 about one of its axes of rotation. There
is a ratio between the amount of actuator movement (e.g. cable
pull, piston motion, or servo rotation/translation) to the amount
of the mechanism's lateral movement (movement in the direction of
the wheel axis). Utilizing a linear derailleur helps to improve
this ration providing greater control to the bicycle user.
The spatial linkage derailleur hanger constrains the floating link
to a rectilinear motion. The relationship between the pulley wheel
axes and the wheel axis is operably adjusted for tuning the
derailleur performance. The disclosed structure allows the angle of
the pulley wheel axes to remain constant throughout the full motion
of the mechanism. In various embodiments, the pulley wheel axes may
remain parallel to the wheel axis throughout full motion of the
mechanism. In other embodiments, the pulley wheel axes may be
skewed relative to the wheel axis. The specific motion of the
spatial linkage derailleur allows the derailleur to be optimized
for efficiency (e.g. less belt or chain wear, improved efficiency,
etc.), shifting quality and minimal chances of chain derailment.
Also, since the linear motion is independent of the floating link
lengths and there is a large amount of freedom for the placement of
the floating link axes on both the fixed and floating link. This
allows the mechanism to be easily controlled due to flexibility in
designing the actuation ratio. In addition the structure lends
itself to multiple configurations with a small envelop. This
provides more flexibility in bike frame design as well as minimizes
the chances of hitting the derailleur on obstacles while
riding.
Having described several embodiments herein, it will be recognized
by those skilled in the art that various modifications, alternative
constructions, and equivalents may be used. The various examples
and embodiments may be employed separately or they may be mixed and
matched in combination to form any iteration of the alternatives.
Additionally, a number of well-known processes and elements have
not been described in order to avoid unnecessarily obscuring the
focus of the present disclosure. Accordingly, the above description
should not be taken as limiting the scope of the invention. Those
skilled in the art will appreciate that the presently disclosed
embodiments teach by way of example and not by limitation.
Therefore, the matter contained in the above description or shown
in the accompanying drawings should be interpreted as illustrative
and not in a limiting sense. For example, while the various figures
shown herein are shown with rear derailleurs, the various concepts
are equally applicable to front derailleurs. In such an embodiment,
the stationary link may be mounted to a bracket, the seat tube, the
crank housing or the like, with the floating link mounting to a
chain guide. The floating link and the chain guide may move in a
substantially rectilinear path aligning the chain with the front
chain rings.
Any and all references specifically identified in the specification
of the present application are expressly incorporated herein in
their entirety by reference thereto. The term "about," as used
herein, should generally be understood to refer to both the
corresponding number and a range of numbers. Moreover, all
numerical ranges herein should be understood to include each whole
integer within the range.
The following claims are intended to cover all generic and specific
features described herein, as well as all statements of the scope
of the present method and system, which, as a matter of language,
might be said to fall there between.
* * * * *
References